Inductive charging is a wireless charging technique that has increasingly been used in low-cost electronics. One inductive charging technique uses a fixed frequency and a variable duty factor PWM sender-side oscillator. Disadvantageously, this approach has required using sensed receiver-side current as feedback when controlling the sender-side PWM duty factor. Such feedback has heretofore been implemented by sensing the receiver-side charge current using a device located on the receiver side and communicating the sensed receiver-side charge current information from the receiver-side across the air gap to sender-side components. This wireless feedback mechanism between sender-side and receiver-side devices adds complexity and is costly, and therefore, it is not suitable for many low-cost electronics applications.
In addition, proper positioning of the sender-side and receiver-side devices relative to each other is important for obtaining efficient inductive power transfer between devices. Existing systems fail to test whether the positioning of the devices is impacting charging, which may cause inefficient or unreliable charging.